The relation between redd counts and Atlantic salmon (Salmo salar) parr populations in the Dennys River, Maine

Abstract

In the Dennys River (eastern Maine), the abundance of age-1 parr of Atlantic salmon (Salmo salar) estimated by electrofishing showed a significant linear relationship ( r 2 = 0.51, p = 0.046) with the redd count obtained 2 years earlier. The relation betweeen age-1 parr and ln(redds) was similar (r 2 = 0.48, p = 0.058). Approximately one half of the variability in parr abundance for the years 1986-1993 could be attributed to the redd count. Similar relationships were observed in the analysis of data from the individual sampling sites. These data suggest that redd counts can be used to predict the future abundance of parr when direct estimates of the numbers of spawners are unavailable and the level of egg deposition is unlikely to result in density-dependent mortality. Site-specific data indicate that redd counts could also be used to identify areas within a river that are understocked by natural reproduction. Resume : Dans la riviere Dennys (est du Maine), l'abondance des tacons de saumon atlantique (Salmo salar) d'un an